Field of the Invention
The present invention relates to a technique for providing a mechanism of data storage for a new web browser in HyperText Markup Language (HTML) 5.
Description of the Related Art
As web applications have become highly functional, various types of function extension have been examined in HTML 5. One of such extended functions is an Application Cache function of caching a file on a web server into a storage area for a web browser. Other extended functions include functions such as WebStorage and Indexed Database (Indexed DB) for storing data into the storage area for the web browser.
For WebStorage, data can be automatically stored in a storage area (a storage area for a web browser) of an information processing terminal such as a personal computer (PC) or a smartphone from the web server providing a website, at a timing when the website is browsed. Such an extended function enables a service provided by the website to be used by using cached data, even if the PC or a mobile terminal browsing the website is disconnected from a network, i.e., offline.
On the other hand, conventionally, there has been a technique for caching, into a storage area for the web browser, content provided by a website although a data amount and the number of data types are smaller than those in the above-mentioned extended function. General web browsers may include one that provides a function of deleting the cached data. More specifically, a user can manually issue an instruction to collectively delete cached data from a setting menu in the web browser. In addition, some web browsers may provide a function of deleting data corresponding to a domain of a website selected by the user.
A method for deleting unnecessary cached data includes a conventional technique as discussed in Japanese Patent Application Laid-Open No. 2012-168778. The conventional technique registers a web application in an image forming apparatus, caches a file required during use of the web application, and deletes, when registration information of the web application is deleted, a related cache together with the registration information.
For the above-mentioned function extension in HTML 5, a capacity of data that can be stored in WebStorage is provided with a limit value for each combination of a protocol called an origin, a host name, and a port. A capacity limit is also provided for entire WebStorage. As a formal specification related to the HTML 5, there is no function of deleting data stored in a local storage area upon the exceedance of a time limit. Accordingly, unless an explicit deletion procedure is taken by the website which causes the data to be stored, the data stored using the above-mentioned extended function remains in the local storage area of a terminal.
In the above-mentioned specification, the following problems may arise. When the user browses a new website, for example, if a data amount already exceeds a storage capacity of WebStorage, a service provided by the new website may be unable to be normally used. When the amount of stored data increases even if it has not reached a capacity limit value, acquisition of data from WebStorage and storage of new data become slow. If a storage capacity is small (e.g., in the case of the mobile terminal), the data stored in WebStorage occupies a large portion of the entire storage capacity of the mobile terminal so that data of another application cannot be stored.
If the use of the above-mentioned various extended functions for storing a file or data into the storage area for the web browser from the website, such as WebStorage, becomes common in the future, it is assumed that an amount of the stored data increases. Thus, the above-mentioned problems become more likely to occur. Therefore, there is a need for a method for appropriately deleting data stored in the storage area for the web browser using the extended functions.
In the above-mentioned technique discussed in Japanese Patent Application Laid-Open No. 2012-168778, when a user deletes a web application, it can be determined that the web application itself is not required. Therefore, related cache data can be deleted without any particular problem.
On the other hand, the file or the data locally stored using the above-mentioned extended functions such as WebStorage is stored during web browsing. An operation of browsing or closing the website in the web browser is considered to be greatly different in intention from an operation of registering or deleting (installing or uninstalling) the web application. More specifically, even if the user closes the website or ends the web browser once after browsing the website, the user may browse the website again when using the web browser next time. In other words, it cannot be determined that the website will not be used in the future, simply based on an action of closing the website in the web browser or ending the web browser. Accordingly, even if the above technique discussed in Japanese Patent Application Laid-Open No. 2012-168778 is considered, it seems difficult to perform control for appropriately deleting the file or the data locally stored using the above-mentioned extended functions such as WebStorage.